The use of process tanks in connection with the coating of articles, in particular metal parts, is well known in the art. The articles are typically positioned within the confines of the tanks and are sprayed with or completely immersed in the chemical solution while in the tank.
The use of immersion tanks in connection with the conveyor line treatment of automobile bodies is disclosed in U.S. Pat. No. 4,196,023, issued to Arthur J. Rowe. Rowe discloses a method for preparing automobile bodies on a conveyor line which utilzes one or more elongate immersion tanks positioned along the assembly line. As the automobile bodies travel on the conveyor line they are routed into the elongate tanks and immersed in the chemical solutions contained in the tanks, pulled out of the tank and moved by the conveyor line to the next stop in the assembly process. When the auto bodies are to be immersed in a series of chemical solutions, the immersion tanks containing these solutions are generally arranged in end-to-end fashion along the conveyor line. One problem with this multiple tank system is that the automobile bodies carry contaminants from one tank to another, resulting in the contamination of the chemical solutions contained in the subsequent tanks. In addition, there is usually a specific processing time associated with each of the chemical solutions. Thus, the tanks must be of sufficient length to ensure that the automobile bodies are exposed to the solution for the appropriate processing time when these bodies are moved at a specified rate by the conveyor line. These tanks occupy a large amount of floor space and require a relatively large volume of chemical solution for each process.
Another problem with conveyor line production system is that the line often shuts down for various reasons. When the line is stopped, the automobile bodies that are currently undergoing treatment in one of the chemical solutions must be removed from the tank after a certain amount of time and accumulated alongside the conveyor until the conveyor restarts. Thus, a large area must be provided for the off-line accumulation of articles undergoing a chemical processing in the event of a conveyor line shutdown.
The present invention is directed to overcoming the problems set forth above.